This invention is generally directed to photoconductive imaging members with certain charge transport components. More specifically, the present invention is directed to layered imaging members with charge transport components containing N,N-bis(biarylyl)aniline and tris(biarylyl)amine derivatives. The aforementioned charge transport components possess a number of advantages including excellent compatibility with resinous binders, such as polycarbonates and polyesters, thereby suppressing or substantially eliminating the undesirable crystallization of these components in the transport layers. Additionally, the charge transport compounds illustrated herein enable photoconductive imaging members that can be selected for electrophotographic imaging and printing processes for an extended number of imaging cycles exceeding, for example, 50,000 cycles. Also, imaging members with the charge transport compounds of the present invention possess excellent high photosensitivity, and possess other advantages, thus enabling, for example, the selection of these members in high speed imaging and printing devices. Furthermore, the imaging members of the present invention exhibit relatively low or negligible dark decay characteristics, thereby permitting the generation of high quality images for imaging and printing applications. In one embodiment of the present invention, the imaging member is comprised of a supporting substrate, a photogenerating layer, and in contact therewith a charge transport layer comprised of N,N-bis(biarylyl)aniline or tris(biarylyl)amine derivatives illustrated herein. The charge or hole transport layer can be located as the top layer of the imaging member, or alternatively it may be situated between the supporting substrate and the photogenerating layer.
The formation and development of electrostatic latent images on the imaging surfaces of photoconductive materials by electrostatic means is well known. Numerous different photoconductive members for use in xerography are known such as selenium, alloys of selenium, layered imaging members comprised of arylamine charge transport layers, reference U.S. Pat. Nos. 4,265,990 and 4,273,846, and imaging members with charge transport layers comprised of polysilylenes, reference U.S. Pat. No. 4,618,551. Nevertheless, layered photoresponsive imaging members with the transport molecules N,N-bis(biarylyl)aniline or tris(biarylyl)amine derivatives of the present invention are equal to or superior to other photoresponsive imaging devices in terms of device long-term stability, device performance, sensitivity to changes in environmental conditions, costs of materials and device fabrication.
There are also known photoreceptor materials comprised of inorganic or organic materials wherein the charge carrier generation and charge carrier transport functions are accomplished by discrete contiguous layers. Additionally, photoreceptor materials are disclosed in the prior art which include an overcoating layer of an electrically insulating polymeric material, and in conjunction with this overcoated type photoreceptor there have been proposed a number of imaging methods.
Specifically, layered photoresponsive devices, including those comprised of generating layers and transport layers, are disclosed in U.S. Pat. No. 4,265,990, and overcoated photoresponsive materials containing a hole injecting layer overcoated with a transport layer, followed by an overcoating of a photogenerating layer and a top coating of an insulating organic resin, reference U.S. Pat. No. 4,251,612. Examples of generating layers disclosed in these patents include trigonal selenium and vanadyl phthalocyanine, while examples of the transport layer that may be employed are comprised of aryldiamines as mentioned therein. The '990 patent is of particular interest in that it discloses layered photoresponsive imaging members similar to those illustrated in the present application with the exception that the charge transporting component of the members of the present invention are comprised of, for example, tris(biarylyl)amine or N,N-bis(biarylyl)aniline compounds. These members can be utilized in electrophotographic methods by, for example, initially charging the member with an electrostatic charge and imagewise exposing to form an electrostatic latent image which can be subsequently developed to form a visible image.
As a result of a patentability search, there were located Japanese Koni abstract J5 8002-849 which discloses a photoconductors comprising a laminate of a carrier generation layer A, and a charge transport layer B which layer contains an amine derivative of Formula I, which amine is similar in some instances to the charge transport compounds of the present invention, a carbazole deriviative of Formula II, and a polymeric organic semiconductor having a condensed aromatic ring or hetero ring in the side chain; Ricoh Japanese abstract 61-132953 which discloses an electrophotographic sensitive body with a trisazo pigment of Formula I, and a charge transfer layer of Formula V, which transfer layer is similar in some instances to the charge transport compounds of the present invention; and as background or collateral interest U.S. Pat. Nos. 4,233,384; 4,273,846; 4,450,218; 4,637,971 and 4,719,963.
Illustrated in related copending application U.S. Ser. No. (not yet assigned,) with the listed inventors Beng Ong, Barkev Keoshkerian, and Giuseppa Baranyi, entitled Photoconductive Imaging Members With Diaryl Biarylamine Charge Transporting Components, the disclosure of which is totally incorporated herein by reference, are layered photoconductive imaging members comprised of a supporting substrate, a photogenerating layer comprised of inorganic, photoconductive pigments, optionally dispersed in an inactive resinous binder, and in contact therewith a charge transport layer comprised of diphenylbiphenylamines of Formula (I) dispersed in resinous binders.
In Belgium Pat. No. 763,540, there is disclosed an electrophotographic member having at least two electrically operative layers, the first layer comprising a photoconductive layer which is capable of photogenerating charge carriers, and injecting the photogenerated hole into a continuous active layer containing a transport organic material which is substantially non-absorbing in the spectral region of intended use, but which is active and that allows injection of photogenerating holes from the photoconductive layer and allows these holes to be transported through the active layer. The active polymers may be mixed with inactive polymers or nonpolymeric materials.
Also, there is illustrated in U.S. Pat. Nos. 4,232,102 and 4,233,383, the disclosures of which are totally incorporated herein by reference, the use of sodium carbonate doped and barium carbonate doped photoresponsive imaging members containing trigonal selenium. Other representative patents disclosing layered photoresponsive devices include U.S. Pat. Nos. 4,115,116; 4,047,949 and 4,081,274.
While imaging members with various charge transporting substances, including some aryl amines, are suitable for their intended purposes there continues to be a need for improved members, particular layered members, which are comprised of hole transporting substances with certain advantages. Further, there continues to be a need for layered imaging members wherein the layers are sufficiently adhered to one another to allow the continuous use of such members in repetitive imaging systems. Also, there continues to be a need for charge transporting substances which are compatible with various resinous binders, such as polycarbonates, thereby ensuring the long-term stability of the photoconductive imaging devices within which they are incorporated. Also, there continues to be a need for charge transporting substances that are also useful as protective overcoating materials, and as interface materials for various imaging members. Furthermore, there is a need for charge transport compounds that are nontoxic, and are inert to the users of the devices, or imaging members within which they are incorporated. A further need resides in the provision of efficient charge transport compounds which are readily accessible synthetically from economical commercial starting materials. Another need resides in the provision of layered photoconductive imaging and printing devices that possess high photosensitives, and thus are useful for high speed imaging and printing applications.